The present invention relates generally to an apparatus for directing filaments, strands and the like. More particularly, the invention relates to a method, system and apparatus all of which utilize a novel wheel apparatus for gathering a plurality of glass filaments into a strand.
Glass fibers or filaments are typically formed today be attenuating a plurality of molten glass streams being drawn through orifices in a glass fiberizing bushing. The filaments are then typically coated with a lubricant binder or sizing composition and gathered into one or more strands by one or more gathering shoes. While various types of gathering shoes or devices are presently being used in the industry, rotating wheel-type shoes are gaining acceptance because they tend to abrade the surface of the strand less than stationary shoes do.
While gaining acceptance, rotating wheels are plagued with what is referred to in the industry as strand wrap-around. Strand wrap-around occurs on the wheel because the filaments tend to stick to the surface of the gathering wheel as the wheel rotates often wrapping many times around the wheel. When this occurs, the attenuation process is interrupted and the filaments have to be removed from the wheel. The process then has to be restarted manually by an operator, which quite obviously is a time consuming task.
U.S. Pat. No. 4,526,598 to Reese et al discusses the strand wrap-around problem and discloses a rotating gathering wheel which is stated to minimize the problem. The wheel has a cylindrical shape and an annular groove with opposing and bottom sides for receiving a plurality of filaments and issuing a bundle or strand of filaments. The annular groove has a plurality of spaced apart radial slots which extend into the center of the shoe for a distance less than the entire radial distance of the shoe. The spacing and number of the spaced apart holes are disclosed as being sufficient to reduce the surface contact area experienced by the filaments and strands by about 20-70% when compared to a shoe with no holes in its gathering surface. This reduced surface contact is stated to reduce the tendency of the filaments and strands to wrap-around the rotating wheel. It is also stated that reductions of less than 20% are generally not enough to noticeably reduce wrapping, while reductions greater than around 70% could result in strand abrasion. While this wheel undoubtedly reduces strand wrap-around in Reese's system (where as illustrated in reese's FIG. 3, the filaments undergo no more than a 30.degree. turn as they travel over the surface of the gathering wheel) Reese's wheel does not work as well in systems wherein the receiving filaments and issuing strands must undergo greater turns, i.e. greater than 30.degree. and thus contact more of the wheel's gathering surface.
U.S. Pat. No. 3,876,404 to Drummond discloses a glass strand traversing apparatus for depositing strand on a forming package wherein the strand makes a significant i.e. estimated to be about 300.degree. turn as it travels on the rotating surface of the apparatus. The traveling surface is composed of a plurality of contact points which the strand engages. The contact points define a plurality of tracks of travel on which the strand rides. Such point contact is stated to minimize contact of the traveling surface with the strand and thus alleviate the problem of strand wrap-around.
As with Reese's wheel, Drummond's traversing apparatus undoubtedly works as intended in the system for which it is designed. However, it's a rather complicated device which would appear to be difficult to assemble and manufacture. It also would appear to wear out rather quickly since the tracks are disclosed as being made of wires which would appear to wear out quickly as the abrasive glass strands traverse the wire's surface. The wire tracks would also be rather difficult to fabricate since each must be produced with a differently shaped, inwardly depressed portion so as to define a nonuniform undulating path for the strands.
Accordingly, while the aforementioned patents reveal that attempts have been made to solve the problem of strand wrap-around, a need still exists for rotating apparatus which not only reduce or minimize the problem of strand wrap-around but also are relatively simple in design and easy to disassemble and reassemble for maintenance purposes.